An ugly duckling problem

The position shown in this week’s main diagram is the starter problem for the Winton British Chess Solving Championship, an annual competition. White must force mate in two moves, against any defence. (White moves, then Black moves, then White delivers checkmate.) For entry details, see the final paragraph.

Many composed positions have an ugly duckling problem. Practical players are accustomed to discernible pawn structures and an approximate balance of material. An irrational starting position, like this one, is apt to draw a little wince. But look deeper, as there is grace and harmony to be found. Composed problems teem with ingenious and beautiful ideas expressed in ways that you might never encounter in practical play.

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For instance, zugzwang (German for ‘compulsion to move’) is an essential motif in endgames, particularly common when just kings and pawns remain. But composers can engineer more elaborate manifestations of this same concept. In ‘mate in two’ problems, moves that create a direct mate are often (though not always) red herrings. An experienced solver will readily consider moves which create a zugzwang wherein White threatens nothing, but any Black move reveals a mating possibility.

Another conspicuous feature of this problem is that the Ke1 and Ra1 are on their starting squares, so castling could be possible if the queen and knight clear the way. The mere fact of Black attacking the b1 square doesn’t preclude this. (In chess problems, by convention, castling is legal, except in very rare cases where you can prove that the king or rook must have moved earlier. Bear that in mind when considering the second puzzle, below.)

In the heat of battle, even world-class players have been befuddled by the castling rules. In 1960, the renowned Soviet grandmaster Yuri Averbakh was playing White against the Australian master Cecil Purdy.